Effect of Compromised Cortical Bone on Implant Load Distribution

Purpose: To investigate photoelastically the difference in load distribution of dental implants with different implant neck designs in intact and compromised bone. Materials and Methods: Composite photoelastic models were fabricated using two different resins to simulate trabecular bone and a 1‐mm thick layer of cortical bone. The following parallel‐sided, threaded implants were centrally located in individual models representing intact and compromised cortical bone: Straumann (4.1‐mm diameter × 12‐mm length), AstraTech (4.0‐mm diameter × 13‐mm length), and 3i (3.75‐mm diameter × 13‐mm length). The compromised cortical bone condition was simulated by contaminating a 1‐mm neck portion with Vaseline to impair the implant–resin interface. Vertical and oblique static loads were applied on the abutments, and the resulting stresses were monitored photoelastically and recorded photograhphically. Results: For the fully intact condition, the highest stresses were observed around the crest and apical region for all implant designs under vertical and inclined loads. There were no appreciable differences in magnitude or distribution between implant types. With compromised cortical bone, for all designs and load directions, higher stresses in the supporting structures were observed. Increased stresses were noted especially at the cortical bone–trabecular bone interface. Somewhat lower stress levels were observed with the 3i implant. Conclusions: The condition of implant–cortical bone contact has considerable influence on stress distribution. A compromised cortical bone condition caused higher level stresses for all implant designs tested.     

Does periodontal disease reflect atherosclerosis in continuous ambulatory peritoneal dialysis patients?

BACKGROUND: Chronic infection and inflammation, including periodontitis, are linked to an increased risk for atherosclerosis. To investigate the possible adverse effects of periodontitis in continuous ambulatory peritoneal dialysis (CAPD) patients, we compared periodontal severity with inflammation and malnutrition, which are associated with poor atherosclerotic outcome in CAPD patients. METHODS: A total of 110 CAPD patients were included in this study to evaluate their clinical periodontal status by using the plaque index, gingival index, and periodontal disease index. Values for nutritional and inflammatory markers and atherosclerotic risk factors were included for analysis with the periodontal index. Analysis of variance, post hoc Tukey's honestly significant difference, univariate and multivariate linear regression analysis, Pearson correlation analysis, and chi2 analysis were used in the evaluation of the data. RESULTS: Poor oral health status was exhibited by 85.5% of our CAPD patients with periodontal disease. We found that age and longer dialysis duration were associated with the severity of periodontitis. Parameters of malnutrition and inflammation and atherosclerotic risk factors also were associated with poor periodontal status. We carried out multiple regression analysis and found that age, albumin level, and duration of dialysis were associated independently with the severity of periodontitis in CAPD patients. A higher percentage of patients in the severe periodontitis group had malnutrition (chi2 = 59.4; P < 0.001), inflammation (chi2 = 60; P < 0.001), and atherosclerosis (chi2 = 65.6; P < 0.001). CONCLUSIONS: Periodontal health is poor in CAPD patients and correlates with markers of malnutrition, inflammation, and atherosclerosis. The diagnosis and treatment of periodontal diseases require better awareness.     

Salivary cortisol and dehydroepiandrosterone (DHEA) levels, psychological factors in patients with oral lichen planus

Objective

The aim of this study was to determine the salivary levels of dehydroepiandrosterone (DHEA) and cortisol and scores of depression, anxiety and stress in patients with oral lichen planus (OLP).

Study design

Thirty-one patients with a diagnosis of OLP were selected; they were matched by sex and age with 31 control patients. Symptoms of depression, anxiety and stress were investigated by the instruments Beck Depression Inventory, Beck Anxiety Inventory and Lipp's Inventory of Stress Symptoms for Adults, respectively. Saliva was collected in the morning and at night for the determination of DHEA and cortisol levels by radioimmunoassay.

Results

There was no significant difference between the groups with respect to depression (P = 0.832), anxiety (P = 0.061) or stress (P = 0.611), or with respect to morning and night salivary levels of DHEA (P = 0.888, P = 0.297) and cortisol (P = 0.443, P = 0.983).

Conclusions

The results suggest an association of OLP with anxiety. However, DHEA and cortisol levels did not differ between groups, which does not support any neuroendocrine aetiology for OLP.     

Effects of surface-conditioning methods on shear bond strength of brackets bonded to different all-ceramic materials

The aims of this study were to investigate the effects of two surface-conditioning methods on the shear bond strength (SBS) of metal brackets bonded to three different all-ceramic materials, and to evaluate the mode of failure after debonding. Twenty feldspathic, 20 fluoro-apatite, and 20 leucite-reinforced ceramic specimens were examined following two surface-conditioning methods: air-particle abrasion (APA) with 25 μm Al(2)O(3) and silica coating with 30 μm Al(2)O(3) particles modified by silica. After silane application, metal brackets were bonded with light cure composite and then stored in distilled water for 1 week and thermocycled (×1000 at 5-55°C for 30 seconds). The SBS of the brackets was measured on a universal testing machine. The ceramic surfaces were examined with a stereomicroscope to determine the amount of composite resin remaining using the adhesive remnant index. Two-way analysis of variance, Tukey's multiple comparison test, and Weibull analysis were used for evaluation of SBS. The lowest SBS was with APA for the fluoro-apatite ceramic (11.82 MPa), which was not significantly different from APA for the feldspathic ceramic (13.58 MPa). The SBS for the fluoro-apatite ceramic was significantly lower than that of leucite-reinforced ceramic with APA (14.82 MPa). The highest SBS value was obtained with silica coating of the leucite-reinforced ceramic (24.17 MPa), but this was not significantly different from the SBS for feldspathic and fluoro-apatite ceramic (23.51 and 22.18 MPa, respectively). The SBS values with silica coating showed significant differences from those of APA. For all samples, the adhesive failures were between the ceramic and composite resin. No ceramic fractures or cracks were observed. Chairside tribochemical silica coating significantly increased the mean bond strength values.     

Diclofenac in hyaluronic acid gel: an alternative treatment for actinic cheilitis

Objective

Actinic cheilitis (AC) is a precancerous lesion of the lip vermillion caused by prolonged exposure to ultraviolet light. The aim of this study was to evaluate the effect of 3% diclofenac in 2.5% hyaluronic acid gel in the treatment of AC.

Methods

Thirty-four patients with chronic AC were treated twice a day with topical diclofenac during a period of 30 to 180 days. The individuals were followed up every 15 days by means of clinical examination and digital photographic documentation.

Results

Of the 27 patients that completed the study, 12 (44%) showed complete remission of the whitish plaques and exfoliative areas, and 15 (56%) had partial remission of the clinical picture of cheilitis. The latter group was submitted to excision of the leukoplakic areas which diagnosis varied from mild to moderate epithelial dysplasia.

Conclusion

The results suggest a promising role for diclofenac in hyaluronic acid gel in the treatment of AC. This treatment has the advantages of not being invasive and showing few side effects.     

Bonding properties of universal adhesives to root canals prepared with different rotary instruments

Statement of problem

Preparation of coronal dentin by using a diamond rotary instrument usually results in higher bond strength values than preparation with tungsten carbide burs, but information is lacking about the influence of rotary instruments on root canals before the bonding of fiber posts.